jordning

Jordning, in electrical engineering, refers to connecting electrical installations to the earth to establish a common reference potential and to provide a low-impedance path for fault currents. In Norwegian usage the term corresponds to grounding or earthing in English. Proper jordning is a fundamental safety and performance feature of electrical systems in buildings, industrial plants, and outdoor networks.

The primary purposes are safety and fault protection. By offering a path for stray and fault currents, jordning reduces the risk of electric shock, enables protective devices to operate reliably, and helps limit overvoltages from lightning or switching. It also provides a stable reference for surge-protection devices and for equipment designed to share a common potential.

Key components include an earth electrode (ground rod or plate), an earth conductor, and an earth bus. Protective earth (PE) conductors form fault paths for safety; functional earth (FE) is used mainly for noise suppression and not for protection. Bonding connections ensure equipotential between exposed conductive parts and other services.

Earth schemes can vary by country. Common residential concepts in many regions are TN, TT, and IT systems. TN-systems connect the source-neutral to earth through the installation's conductors; TT systems use a separate local earth; IT systems keep the supply only indirectly earthed. Each has different implications for protective devices and maintenance.

Standards such as IEC 60364 (Electrical Installations for Buildings) and national regulations govern jordning design, installation, and testing. Practices differ by region, with some requiring specific earth resistance values, bonding rules, and periodic verification to ensure safety and reliability.

Maintenance typically includes measuring earth resistance, inspecting electrodes and conductors for corrosion or damage, and verifying continuity of bonding networks, especially after renovations or soil changes.